It is often advantageous to monitor and carry out an analysis of both the rate of production and the composition of a person's sweat while they are performing strenuous physical exertion, since such knowledge enables the individual to more accurately replenish lost sweat fluid and electrolytes. The analysis of sweat may also be useful for other reasons, such as diagnosing cystic fibrosis, since such analysis currently forms the basis on which such a diagnosis is made.